1
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Zhang H, Zhu JK. Epigenetic gene regulation in plants and its potential applications in crop improvement. Nat Rev Mol Cell Biol 2024:10.1038/s41580-024-00769-1. [PMID: 39192154 DOI: 10.1038/s41580-024-00769-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/18/2024] [Indexed: 08/29/2024]
Abstract
DNA methylation, also known as 5-methylcytosine, is an epigenetic modification that has crucial functions in plant growth, development and adaptation. The cellular DNA methylation level is tightly regulated by the combined action of DNA methyltransferases and demethylases. Protein complexes involved in the targeting and interpretation of DNA methylation have been identified, revealing intriguing roles of methyl-DNA binding proteins and molecular chaperones. Structural studies and in vitro reconstituted enzymatic systems have provided mechanistic insights into RNA-directed DNA methylation, the main pathway catalysing de novo methylation in plants. A better understanding of the regulatory mechanisms will enable locus-specific manipulation of the DNA methylation status. CRISPR-dCas9-based epigenome editing tools are being developed for this goal. Given that DNA methylation patterns can be stably transmitted through meiosis, and that large phenotypic variations can be contributed by epimutations, epigenome editing holds great promise in crop breeding by creating additional phenotypic variability on the same genetic material.
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Affiliation(s)
- Heng Zhang
- Department of Genetics and Developmental Science, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China.
| | - Jian-Kang Zhu
- Institute of Advanced Biotechnology and School of Medicine, Southern University of Science and Technology, Shenzhen, China.
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2
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Kan Q, Li Q. Post-transcriptional and translational regulation of plant gene expression by transposons. CURRENT OPINION IN PLANT BIOLOGY 2023; 75:102438. [PMID: 37619514 DOI: 10.1016/j.pbi.2023.102438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 07/22/2023] [Accepted: 07/22/2023] [Indexed: 08/26/2023]
Abstract
Transposons are mobile DNA sequences that can move within the genome and integrate in new genomic locations. They are widespread in eukaryotes and prokaryotes and can influence gene expression when landing within or nearby a gene. Although transposon-induced regulation of gene expression at the transcriptional level has been extensively studied, there has been less focus on regulation at the post-transcriptional and translational levels. Recent studies in maize (Zea mays) and other plant species suggest that transposon insertions can affect RNA processing, RNA stability, protein translation and protein stability. We will describe the diverse mechanisms by which transposons can influence gene expression at the post-transcriptional and translational levels, and discuss the interactions between these mechanisms.
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Affiliation(s)
- Qiuxin Kan
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
| | - Qing Li
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China; Hubei Hongshan Laboratory, Wuhan 430070, China.
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3
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Berthelier J, Furci L, Asai S, Sadykova M, Shimazaki T, Shirasu K, Saze H. Long-read direct RNA sequencing reveals epigenetic regulation of chimeric gene-transposon transcripts in Arabidopsis thaliana. Nat Commun 2023; 14:3248. [PMID: 37277361 DOI: 10.1038/s41467-023-38954-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 05/21/2023] [Indexed: 06/07/2023] Open
Abstract
Transposable elements (TEs) are accumulated in both intergenic and intragenic regions in plant genomes. Intragenic TEs often act as regulatory elements of associated genes and are also co-transcribed with genes, generating chimeric TE-gene transcripts. Despite the potential impact on mRNA regulation and gene function, the prevalence and transcriptional regulation of TE-gene transcripts are poorly understood. By long-read direct RNA sequencing and a dedicated bioinformatics pipeline, ParasiTE, we investigated the transcription and RNA processing of TE-gene transcripts in Arabidopsis thaliana. We identified a global production of TE-gene transcripts in thousands of A. thaliana gene loci, with TE sequences often being associated with alternative transcription start sites or transcription termination sites. The epigenetic state of intragenic TEs affects RNAPII elongation and usage of alternative poly(A) signals within TE sequences, regulating alternative TE-gene isoform production. Co-transcription and inclusion of TE-derived sequences into gene transcripts impact regulation of RNA stability and environmental responses of some loci. Our study provides insights into TE-gene interactions that contributes to mRNA regulation, transcriptome diversity, and environmental responses in plants.
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Grants
- JP20H02995 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- JP22H00364 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- JP20H05909 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
- JP20H05913 Ministry of Education, Culture, Sports, Science and Technology (MEXT)
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Affiliation(s)
- Jérémy Berthelier
- Plant Epigenetics Unit, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan.
| | - Leonardo Furci
- Plant Epigenetics Unit, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan
| | - Shuta Asai
- Center for Sustainable Resource Science, RIKEN, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan
| | - Munissa Sadykova
- Plant Epigenetics Unit, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan
| | - Tomoe Shimazaki
- Plant Epigenetics Unit, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan
| | - Ken Shirasu
- Center for Sustainable Resource Science, RIKEN, 1-7-22 Suehiro-cho, Tsurumi, Yokohama, Kanagawa, 230-0045, Japan
| | - Hidetoshi Saze
- Plant Epigenetics Unit, Okinawa Institute of Science and Technology Graduate University (OIST), 1919-1 Tancha, Onna-son, Kunigami-gun, Okinawa, 904-0495, Japan.
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4
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Hari Sundar G V, Swetha C, Basu D, Pachamuthu K, Raju S, Chakraborty T, Mosher RA, Shivaprasad PV. Plant polymerase IV sensitizes chromatin through histone modifications to preclude spread of silencing into protein-coding domains. Genome Res 2023; 33:715-728. [PMID: 37277199 PMCID: PMC10317121 DOI: 10.1101/gr.277353.122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 04/16/2023] [Indexed: 06/07/2023]
Abstract
Across eukaryotes, gene regulation is manifested via chromatin states roughly distinguished as heterochromatin and euchromatin. The establishment, maintenance, and modulation of the chromatin states is mediated using several factors including chromatin modifiers. However, factors that avoid the intrusion of silencing signals into protein-coding genes are poorly understood. Here we show that a plant specific paralog of RNA polymerase (Pol) II, named Pol IV, is involved in avoidance of facultative heterochromatic marks in protein-coding genes, in addition to its well-established functions in silencing repeats and transposons. In its absence, H3K27 trimethylation (me3) mark intruded the protein-coding genes, more profoundly in genes embedded with repeats. In a subset of genes, spurious transcriptional activity resulted in small(s) RNA production, leading to post-transcriptional gene silencing. We show that such effects are significantly pronounced in rice, a plant with a larger genome with distributed heterochromatin compared with Arabidopsis Our results indicate the division of labor among plant-specific polymerases, not just in establishing effective silencing via sRNAs and DNA methylation but also in influencing chromatin boundaries.
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Affiliation(s)
- Vivek Hari Sundar G
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bangalore 560065, India
| | - Chenna Swetha
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bangalore 560065, India
| | - Debjani Basu
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bangalore 560065, India
| | - Kannan Pachamuthu
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bangalore 560065, India
| | - Steffi Raju
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bangalore 560065, India
| | - Tania Chakraborty
- School of Plant Sciences, The University of Arizona, Tucson, Arizona 85721, USA
| | - Rebecca A Mosher
- School of Plant Sciences, The University of Arizona, Tucson, Arizona 85721, USA
| | - P V Shivaprasad
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bangalore 560065, India;
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5
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Wang X, Wong CC, Chen H, Fu K, Shi L, Su H, Guo S, Gou H, Hu X, Zhang L, Ji J, Yu J. The N 6-methyladenine DNA demethylase ALKBH1 promotes gastric carcinogenesis by disrupting NRF1 binding capacity. Cell Rep 2023; 42:112279. [PMID: 36989111 DOI: 10.1016/j.celrep.2023.112279] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 01/20/2023] [Accepted: 03/03/2023] [Indexed: 03/30/2023] Open
Abstract
DNA N6-methyladenine (6mA) is an epigenetic modification that regulates various biological processes. Here, we show that gastric cancer (GC) cells and tumors display a marked reduction in 6mA levels compared with normal gastric tissues and cells. 6mA is abundant in the surrounding transcription start sites and occurs at consensus motifs. Among the 6mA regulators, ALKBH1, a demethylase, is significantly overexpressed in GC tissues compared with adjacent normal tissues. Moreover, high ALKBH1 expression is associated with poor survival of patients with GC. ALKBH1 knockout in mice impairs chemically induced gastric carcinogenesis. Mechanistically, ALKBH1 mediates DNA 6mA demethylation to repress gene expression. In particular, the 6mA sites are enriched in NRF1 binding sequences and targeted for demethylation by ALKBH1. ALKBH1-induced 6mA demethylation inhibits NRF1-driven transcription of downstream targets, including multiple genes involved in the AMP-activated protein kinase (AMPK) signaling pathway. Accordingly, ALKBH1 suppresses AMPK signaling, causing a metabolic shift toward the Warburg effect, which facilitates tumorigenesis.
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Affiliation(s)
- Xiaohong Wang
- Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong SAR, China; Key Laboratory of Carcinogenesis and Translational Research, Peking University Cancer Hospital and Institute, Beijing, China
| | - Chi Chun Wong
- Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Huarong Chen
- Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Kaili Fu
- Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Lingxue Shi
- Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Hao Su
- Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Shang Guo
- Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Hongyan Gou
- Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Xiaoxu Hu
- Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Lianhai Zhang
- Key Laboratory of Carcinogenesis and Translational Research, Peking University Cancer Hospital and Institute, Beijing, China
| | - Jiafu Ji
- Key Laboratory of Carcinogenesis and Translational Research, Peking University Cancer Hospital and Institute, Beijing, China.
| | - Jun Yu
- Institute of Digestive Disease and Department of Medicine and Therapeutics, State Key Laboratory of Digestive Disease, Li Ka Shing Institute of Health Sciences, CUHK Shenzhen Research Institute, The Chinese University of Hong Kong, Hong Kong SAR, China.
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6
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Li H, Sun J, Dong Y, Huang Y, Wu L, Xi C, Su Z, Xiao Y, Zhang C, Liang Y, Li Y, Lin Z, Shen L, Zuo Y, Abudureheman A, Yin J, Wang H, Kong X, Le R, Gao S, Zhang Y. Remodeling of H3K9me3 during the pluripotent to totipotent-like state transition. Stem Cell Reports 2023; 18:449-462. [PMID: 36638787 PMCID: PMC9968986 DOI: 10.1016/j.stemcr.2022.12.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Revised: 12/06/2022] [Accepted: 12/08/2022] [Indexed: 01/14/2023] Open
Abstract
Multiple chromatin modifiers associated with H3K9me3 play important roles in the transition from embryonic stem cells to 2-cell (2C)-like cells. However, it remains elusive how H3K9me3 is remodeled and its association with totipotency. Here, we integrated transcriptome and H3K9me3 profiles to conduct a detailed comparison of 2C embryos and 2C-like cells. Globally, H3K9me3 is highly preserved and H3K9me3 dynamics within the gene locus is not associated with gene expression change during 2C-like transition. Promoter-deposited H3K9me3 plays non-repressive roles in the activation of genes during 2C-like transition. In contrast, transposable elements, residing in the nearby regions of up-regulated genes, undergo extensive elimination of H3K9me3 and are tended to be induced in 2C-like transitions. Furthermore, a large fraction of trophoblast stem cell-specific enhancers undergo loss of H3K9me3 exclusively in MERVL+/Zscan4+ cells. Our study therefore reveals the unique H3K9me3 profiles of 2C-like cells, facilitating the further exploration of totipotency.
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Affiliation(s)
- Hu Li
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Frontier Science Center for Stem Cells, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China; CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China; School of Life Sciences and Technology, Xinxiang Medical University, Xinxiang, Henan Province 453003, China
| | - Jiatong Sun
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Frontier Science Center for Stem Cells, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Yu Dong
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Frontier Science Center for Stem Cells, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Yixin Huang
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Frontier Science Center for Stem Cells, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Li Wu
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Frontier Science Center for Stem Cells, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Chenxiang Xi
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Frontier Science Center for Stem Cells, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Zhongqu Su
- College of Animal Science and Technology, Shandong Key Laboratory of Animal Bioengineering and Disease Prevention, Shandong Agricultural University, Taian, Shandong, 271018, China
| | - Yihan Xiao
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Frontier Science Center for Stem Cells, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Chuyu Zhang
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Frontier Science Center for Stem Cells, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Yuwei Liang
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Frontier Science Center for Stem Cells, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Yujun Li
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Frontier Science Center for Stem Cells, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Zhiyi Lin
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Frontier Science Center for Stem Cells, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Lu Shen
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Frontier Science Center for Stem Cells, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Yixing Zuo
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Frontier Science Center for Stem Cells, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Abuduwaili Abudureheman
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Frontier Science Center for Stem Cells, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Jiqing Yin
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Frontier Science Center for Stem Cells, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Hong Wang
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Frontier Science Center for Stem Cells, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Xiangyin Kong
- CAS Key Laboratory of Tissue Microenvironment and Tumor, Shanghai Institute of Nutrition and Health, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Rongrong Le
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Frontier Science Center for Stem Cells, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China.
| | - Shaorong Gao
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Frontier Science Center for Stem Cells, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China.
| | - Yanping Zhang
- Clinical and Translational Research Center of Shanghai First Maternity & Infant Hospital, Frontier Science Center for Stem Cells, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China.
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7
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Molecular basis of locus-specific H3K9 methylation catalyzed by SUVH6 in plants. Proc Natl Acad Sci U S A 2023; 120:e2208525120. [PMID: 36580600 PMCID: PMC9910501 DOI: 10.1073/pnas.2211155120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Dimethylated histone H3 Lys9 (H3K9me2) is a conserved heterochromatic mark catalyzed by SUPPRESSOR OF VARIEGATION 3-9 HOMOLOG (SUVH) methyltransferases in plants. However, the mechanism underlying the locus specificity of SUVH enzymes has long been elusive. Here, we show that a conserved N-terminal motif is essential for SUVH6-mediated H3K9me2 deposition in planta. The SUVH6 N-terminal peptide can be recognized by the bromo-adjacent homology (BAH) domain of the RNA- and chromatin-binding protein ANTI-SILENCING 1 (ASI1), which has been shown to function in a complex to confer gene expression regulation. Structural data indicate that a classic aromatic cage of ASI1-BAH domain specifically recognizes an arginine residue of SUVH6 through extensive hydrogen bonding interactions. A classic aromatic cage of ASI1 specifically recognizes an arginine residue of SUVH6 through extensive cation-π interactions, playing a key role in recognition. The SUVH6-ASI1 module confers locus-specific H3K9me2 deposition at most SUVH6 target loci and gives rise to distinct regulation of gene expression depending on the target loci, either conferring transcriptional silencing or posttranscriptional processing of mRNA. More importantly, such mechanism is conserved in multiple plant species, indicating a coordinated evolutionary process between SUVH6 and ASI1. In summary, our findings uncover a conserved mechanism for the locus specificity of H3K9 methylation in planta. These findings provide mechanistic insights into the delicate regulation of H3K9 methylation homeostasis in plants.
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8
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Sammarco I, Pieters J, Salony S, Toman I, Zolotarov G, Lafon Placette C. Epigenetic targeting of transposon relics: beating the dead horses of the genome? Epigenetics 2022; 17:1331-1344. [PMID: 36255200 PMCID: PMC9586680 DOI: 10.1080/15592294.2021.2022066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Transposable elements (TEs) have been seen as selfish genetic elements that can propagate in a host genome. Their propagation success is however hindered by a combination of mechanisms such as mutations, selection, and their epigenetic silencing by the host genome. As a result, most copies of TEs in a given genome are dead relics: their sequence is too degenerated to allow any transposition. Nevertheless, these TE relics often, but not always, remain epigenetically silenced, and if not to prevent transposition anymore, one can wonder the reason for this phenomenon. The mere self-perpetuating loop inherent to epigenetic silencing could alone explain that even when inactive, TE copies remain silenced. Beyond this process, nevertheless, antagonistic selective forces are likely to act on TE relic silencing. Especially, without the benefit of preventing transposition, TE relic silencing may prove deleterious to the host fitness, suggesting that the maintenance of TE relic silencing is the result of a fine, and perhaps case-by-case, evolutionary trade-off between beneficial and deleterious effects. Ultimately, the release of TE relics silencing may provide a 'safe' ground for adaptive epimutations to arise. In this review, we provide an overview of these questions in both plants and animals.
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Affiliation(s)
- Iris Sammarco
- Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic,Institute of Botany, Czech Academy of Sciences, Pruhonice, Czech Republic
| | - Janto Pieters
- Laboratory of Pollen Biology, Institute of Experimental Botany, Czech Academy of Science, Prague, Czech Republic,Department of Plant Experimental Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Susnata Salony
- Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic
| | - Izabela Toman
- Department of Anthropology and Human Genetics, Faculty of Science, Charles University, Prague, Czech Republic
| | - Grygoriy Zolotarov
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
| | - Clément Lafon Placette
- Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic,CONTACT Clément Lafon Placette Department of Botany, Faculty of Science, Charles University, PragueCZ-128 01, Czech Republic
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9
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Fingerhut JM, Yamashita YM. The regulation and potential functions of intronic satellite DNA. Semin Cell Dev Biol 2022; 128:69-77. [PMID: 35469677 DOI: 10.1016/j.semcdb.2022.04.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 04/11/2022] [Accepted: 04/12/2022] [Indexed: 12/15/2022]
Abstract
Satellite DNAs are arrays of tandem repeats found in the eukaryotic genome. They are mainly found in pericentromeric heterochromatin and have been believed to be mostly inert, leading satellite DNAs to be erroneously regarded as junk. Recent studies have started to elucidate the function of satellite DNA, yet little is known about the peculiar case where satellite DNA is found within the introns of protein coding genes, resulting in incredibly large introns, a phenomenon termed intron gigantism. Studies in Drosophila demonstrated that satellite DNA-containing introns are transcribed with the gene and require specialized mechanisms to overcome the burdens imposed by the extremely long stretches of repetitive DNA. Whether intron gigantism confers any benefit or serves any functional purpose for cells and/or organisms remains elusive. Here we review our current understanding of intron gigantism: where it is found, the challenges it imposes, how it is regulated and what purpose it may serve.
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Affiliation(s)
- Jaclyn M Fingerhut
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA; Howard Hughes Medical Institute, Cambridge, MA, USA.
| | - Yukiko M Yamashita
- Whitehead Institute for Biomedical Research and Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA; Howard Hughes Medical Institute, Cambridge, MA, USA.
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10
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Ugarković Đ, Sermek A, Ljubić S, Feliciello I. Satellite DNAs in Health and Disease. Genes (Basel) 2022; 13:genes13071154. [PMID: 35885937 PMCID: PMC9324158 DOI: 10.3390/genes13071154] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 06/20/2022] [Accepted: 06/24/2022] [Indexed: 12/10/2022] Open
Abstract
Tandemly repeated satellite DNAs are major components of centromeres and pericentromeric heterochromatin which are crucial chromosomal elements responsible for accurate chromosome segregation. Satellite DNAs also contribute to genome evolution and the speciation process and are important for the maintenance of the entire genome inside the nucleus. In addition, there is increasing evidence for active and tightly regulated transcription of satellite DNAs and for the role of their transcripts in diverse processes. In this review, we focus on recent discoveries related to the regulation of satellite DNA expression and the role of their transcripts, either in heterochromatin establishment and centromere function or in gene expression regulation under various biological contexts. We discuss the role of satellite transcripts in the stress response and environmental adaptation as well as consequences of the dysregulation of satellite DNA expression in cancer and their potential use as cancer biomarkers.
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Affiliation(s)
- Đurđica Ugarković
- Department of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia; (A.S.); (S.L.)
- Correspondence: (Đ.U.); (I.F.); Tel.: +385-1-4561-083 (D.U.); +39-081-746-4317 (I.F.)
| | - Antonio Sermek
- Department of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia; (A.S.); (S.L.)
| | - Sven Ljubić
- Department of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia; (A.S.); (S.L.)
| | - Isidoro Feliciello
- Department of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, HR-10000 Zagreb, Croatia; (A.S.); (S.L.)
- Department of Clinical Medicine and Surgery, School of Medicine, University of Naples Federico II, Via Pansini 5, 80131 Naples, Italy
- Correspondence: (Đ.U.); (I.F.); Tel.: +385-1-4561-083 (D.U.); +39-081-746-4317 (I.F.)
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11
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Ying H, Hayward DC, Klimovich A, Bosch TCG, Baldassarre L, Neeman T, Forêt S, Huttley G, Reitzel AM, Fraune S, Ball EE, Miller DJ. The role of DNA methylation in genome defense in Cnidaria and other invertebrates. Mol Biol Evol 2022; 39:6516040. [PMID: 35084499 PMCID: PMC8857917 DOI: 10.1093/molbev/msac018] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Considerable attention has recently been focused on the potential involvement of DNA methylation in regulating gene expression in cnidarians. Much of this work has been centered on corals, in the context of changes in methylation perhaps facilitating adaptation to higher seawater temperatures and other stressful conditions. Although first proposed more than 30 years ago, the possibility that DNA methylation systems function in protecting animal genomes against the harmful effects of transposon activity has largely been ignored since that time. Here, we show that transposons are specifically targeted by the DNA methylation system in cnidarians, and that the youngest transposons (i.e., those most likely to be active) are most highly methylated. Transposons in longer and highly active genes were preferentially methylated and, as transposons aged, methylation levels declined, reducing the potentially harmful side effects of CpG methylation. In Cnidaria and a range of other invertebrates, correlation between the overall extent of methylation and transposon content was strongly supported. Present transposon burden is the dominant factor in determining overall level of genomic methylation in a range of animals that diverged in or before the early Cambrian, suggesting that genome defense represents the ancestral role of CpG methylation.
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Affiliation(s)
- Hua Ying
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - David C Hayward
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | | | - Thomas C G Bosch
- Zoological Institute, Christian Albrechts University, Kiel, Germany.,Collaborative Research Center for the Origin and Function of Metaorganisms, Christian Albrechts University, Kiel, Germany
| | - Laura Baldassarre
- Department of Zoology and Organismal Interactions, Heinrich-Heine-University Düsseldorf, Germany
| | - Teresa Neeman
- Biological Data Institute, Australian National University, Canberra, ACT, Australia
| | - Sylvain Forêt
- Research School of Biology, Australian National University, Canberra, ACT, Australia.,ARC Centre of Excellence for Coral Reef Studies, Australian National University, Canberra, ACT, Australia
| | - Gavin Huttley
- Research School of Biology, Australian National University, Canberra, ACT, Australia
| | - Adam M Reitzel
- Department of Biological Sciences, University of North Carolina, Charlotte, USA
| | - Sebastian Fraune
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia
| | - Eldon E Ball
- Research School of Biology, Australian National University, Canberra, ACT, Australia.,ARC Centre of Excellence for Coral Reef Studies, Australian National University, Canberra, ACT, Australia
| | - David J Miller
- ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, Queensland, Australia.,College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland, Australia.,Centre for Tropical Bioinformatics and Molecular Biology, James Cook University, Townsville, Queensland, Australia.,Marine Climate Change Unit, Okinawa Institute of Science and Technology, Japan
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12
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Ichiyanagi K, Saito K. The fifth Japanese meeting on biological function and evolution through interactions between hosts and transposable elements. Mob DNA 2022; 13:3. [PMID: 35027075 PMCID: PMC8756742 DOI: 10.1186/s13100-022-00261-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 01/01/2022] [Indexed: 12/02/2022] Open
Abstract
The fifth Japanese meeting on host–transposon interactions, titled “Biological Function and Evolution through Interactions between Hosts and Transposable Elements (TEs),” was held online on August 26–27, 2021. The meeting was supported by National Institute of Genetics and aimed to bring together researchers studying the diverse roles of TEs in genome function and evolution, as well as host defense systems against TE mobility by chromatin and RNA modifications and protein-protein interactions. Here, we present the highlights of the talks.
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Affiliation(s)
- Kenji Ichiyanagi
- Laboratory of Genome and Epigenome Dynamics, Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8601, Japan.
| | - Kuniaki Saito
- Invertebrate Genetics Laboratory, National Institute of Genetics, Yata 1111, Mishima, Shizuoka, 411-8540, Japan.
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13
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Hannan Parker A, Wilkinson SW, Ton J. Epigenetics: a catalyst of plant immunity against pathogens. THE NEW PHYTOLOGIST 2022; 233:66-83. [PMID: 34455592 DOI: 10.1111/nph.17699] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 07/20/2021] [Indexed: 05/11/2023]
Abstract
The plant immune system protects against pests and diseases. The recognition of stress-related molecular patterns triggers localised immune responses, which are often followed by longer-lasting systemic priming and/or up-regulation of defences. In some cases, this induced resistance (IR) can be transmitted to following generations. Such transgenerational IR is gradually reversed in the absence of stress at a rate that is proportional to the severity of disease experienced in previous generations. This review outlines the mechanisms by which epigenetic responses to pathogen infection shape the plant immune system across expanding time scales. We review the cis- and trans-acting mechanisms by which stress-inducible epigenetic changes at transposable elements (TEs) regulate genome-wide defence gene expression and draw particular attention to one regulatory model that is supported by recent evidence about the function of AGO1 and H2A.Z in transcriptional control of defence genes. Additionally, we explore how stress-induced mobilisation of epigenetically controlled TEs acts as a catalyst of Darwinian evolution by generating (epi)genetic diversity at environmentally responsive genes. This raises questions about the long-term evolutionary consequences of stress-induced diversification of the plant immune system in relation to the long-held dichotomy between Darwinian and Lamarckian evolution.
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Affiliation(s)
- Adam Hannan Parker
- Department of Animal and Plant Sciences, Institute for Sustainable Food, Western Bank, University of Sheffield, Sheffield, S10 2TN, UK
| | - Samuel W Wilkinson
- Department of Animal and Plant Sciences, Institute for Sustainable Food, Western Bank, University of Sheffield, Sheffield, S10 2TN, UK
| | - Jurriaan Ton
- Department of Animal and Plant Sciences, Institute for Sustainable Food, Western Bank, University of Sheffield, Sheffield, S10 2TN, UK
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14
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Sollitto M, Kenny NJ, Greco S, Tucci CF, Calcino AD, Gerdol M. Detecting Structural Variants and Associated Gene Presence-Absence Variation Phenomena in the Genomes of Marine Organisms. Methods Mol Biol 2022; 2498:53-76. [PMID: 35727540 DOI: 10.1007/978-1-0716-2313-8_4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
As complete genomes become easier to attain, even from previously difficult-to-sequence species, and as genomic resequencing becomes more routine, it is becoming obvious that genomic structural variation is more widespread than originally thought and plays an important role in maintaining genetic variation in populations. Structural variants (SVs) and associated gene presence-absence variation (PAV) can be important players in local adaptation, allowing the maintenance of genetic variation and taking part in other evolutionarily relevant phenomena. While recent studies have highlighted the importance of structural variation in Mollusca, the prevalence of this phenomenon in the broader context of marine organisms remains to be fully investigated.Here, we describe a straightforward and broadly applicable method for the identification of SVs in fully assembled diploid genomes, leveraging the same reads used for assembly. We also explain a gene PAV analysis protocol, which could be broadly applied to any species with a fully sequenced reference genome available. Although the strength of these approaches have been tested and proven in marine invertebrates, which tend to have high levels of heterozygosity, possibly due to their lifestyle traits, they are also applicable to other species across the tree of life, providing a ready means to begin investigations into this potentially widespread phenomena.
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Affiliation(s)
- Marco Sollitto
- Department of Life Sciences, Università degli Studi di Trieste, Trieste, Italy
| | - Nathan J Kenny
- Faculty of Health and Life Sciences, Oxford Brookes, Oxford, UK
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Samuele Greco
- Department of Life Sciences, Università degli Studi di Trieste, Trieste, Italy
| | | | - Andrew D Calcino
- Department of Evolutionary Biology, Integrative Zoology, University of Vienna, Vienna, Austria
| | - Marco Gerdol
- Department of Life Sciences, Università degli Studi di Trieste, Trieste, Italy.
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15
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You L, Lin J, Xu H, Chen C, Chen J, Zhang J, Zhang J, Li Y, Ye C, Zhang H, Jiang J, Zhu J, Li QQ, Duan C. Intragenic heterochromatin-mediated alternative polyadenylation modulates miRNA and pollen development in rice. THE NEW PHYTOLOGIST 2021; 232:835-852. [PMID: 34289124 PMCID: PMC9292364 DOI: 10.1111/nph.17635] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 06/25/2021] [Indexed: 05/02/2023]
Abstract
Despite a much higher proportion of intragenic heterochromatin-containing genes in crop genomes, the importance of intragenic heterochromatin in crop development remains unclear. Intragenic heterochromatin can be recognised by a protein complex, ASI1-AIPP1-EDM2 (AAE) complex, to regulate alternative polyadenylation. Here, we investigated the impact of rice ASI1 on global poly(A) site usage through poly(A) sequencing and ASI1-dependent regulation on rice development. We found that OsASI1 is essential for rice pollen development and flowering. OsASI1 dysfunction has an important impact on global poly(A) site usage, which is closely related to heterochromatin marks. Intriguingly, OsASI1 interacts with the intronic heterochromatin of OsXRNL, a nuclear XRN family exonuclease gene involved in the processing of an miRNA precursor, to promote the processing of full-length OsXRNL and regulate miRNA abundance. We found that OsASI1-mediated regulation of pollen development partially depends on OsXRNL. Finally, we characterised the rice AAE complex and its involvement in alternative polyadenylation and pollen development. Our findings help to elucidate an epigenetic mechanism governing miRNA abundance and rice development, and provide a valuable resource for studying the epigenetic mechanisms of many important processes in crops.
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Affiliation(s)
- Li‐Yuan You
- Shanghai Center for Plant Stress Biology and Center of Excellence in Molecular Plant SciencesChinese Academy of ScienceShanghai201602China
- University of Chinese Academy of SciencesBeijing100049China
| | - Juncheng Lin
- Key Laboratory of the Ministry of Education for Coastal and Wetland EcosystemsCollege of the Environment and EcologyXiamen UniversityXiamenFujian361102China
| | - Hua‐Wei Xu
- Shanghai Center for Plant Stress Biology and Center of Excellence in Molecular Plant SciencesChinese Academy of ScienceShanghai201602China
- College of AgricultureHenan University of Science and TechnologyLuoyang471023China
| | - Chun‐Xiang Chen
- Shanghai Center for Plant Stress Biology and Center of Excellence in Molecular Plant SciencesChinese Academy of ScienceShanghai201602China
- University of Chinese Academy of SciencesBeijing100049China
| | - Jun‐Yu Chen
- Shanghai Center for Plant Stress Biology and Center of Excellence in Molecular Plant SciencesChinese Academy of ScienceShanghai201602China
- University of Chinese Academy of SciencesBeijing100049China
| | - Jinshan Zhang
- Shanghai Center for Plant Stress Biology and Center of Excellence in Molecular Plant SciencesChinese Academy of ScienceShanghai201602China
| | - Jian Zhang
- Shanghai Center for Plant Stress Biology and Center of Excellence in Molecular Plant SciencesChinese Academy of ScienceShanghai201602China
- University of Chinese Academy of SciencesBeijing100049China
| | - Ying‐Xin Li
- Shanghai Center for Plant Stress Biology and Center of Excellence in Molecular Plant SciencesChinese Academy of ScienceShanghai201602China
- University of Chinese Academy of SciencesBeijing100049China
| | - Congting Ye
- Key Laboratory of the Ministry of Education for Coastal and Wetland EcosystemsCollege of the Environment and EcologyXiamen UniversityXiamenFujian361102China
| | - Hui Zhang
- College of Life ScienceShanghai Normal UniversityShanghai200234China
| | - Jing Jiang
- State Key Laboratory of Crop Stress Adaptation and ImprovementSchool of Life SciencesHenan UniversityKaifeng475004China
| | - Jian‐Kang Zhu
- Shanghai Center for Plant Stress Biology and Center of Excellence in Molecular Plant SciencesChinese Academy of ScienceShanghai201602China
| | - Qingshun Q. Li
- Key Laboratory of the Ministry of Education for Coastal and Wetland EcosystemsCollege of the Environment and EcologyXiamen UniversityXiamenFujian361102China
- Graduate College of Biomedical SciencesWestern University of Health SciencesPomonaCA91766USA
| | - Cheng‐Guo Duan
- Shanghai Center for Plant Stress Biology and Center of Excellence in Molecular Plant SciencesChinese Academy of ScienceShanghai201602China
- University of Chinese Academy of SciencesBeijing100049China
- State Key Laboratory of Crop Stress Adaptation and ImprovementSchool of Life SciencesHenan UniversityKaifeng475004China
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16
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Feliciello I, Pezer Ž, Sermek A, Bruvo Mađarić B, Ljubić S, Ugarković Đ. Satellite DNA-Mediated Gene Expression Regulation: Physiological and Evolutionary Implication. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2021; 60:145-167. [PMID: 34386875 DOI: 10.1007/978-3-030-74889-0_6] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Satellite DNAs are tandemly repeated sequences organized in large clusters within (peri)centromeric and/or subtelomeric heterochromatin. However, in many species, satellite DNAs are not restricted to heterochromatin but are also dispersed as short arrays within euchromatin. Such genomic organization together with transcriptional activity seems to be a prerequisite for the gene-modulatory effect of satellite DNAs which was first demonstrated in the beetle Tribolium castaneum upon heat stress. Namely, enrichment of a silent histone mark at euchromatic repeats of a major beetle satellite DNA results in epigenetic silencing of neighboring genes. In addition, human satellite III transcripts induced by heat shock contribute to genome-wide gene silencing, providing protection against stress-induced cell death. Gene silencing mediated by satellite RNA was also shown to be fundamental for the early embryonic development of the mosquito Aedes aegypti. Apart from a physiological role during embryogenesis and heat stress response, activation of satellite DNAs in terms of transcription and proliferation can have an evolutionary impact. Spreading of satellite repeats throughout euchromatin promotes the variation of epigenetic landscapes and gene expression diversity, contributing to the evolution of gene regulatory networks and to genome adaptation in fluctuating environmental conditions.
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Affiliation(s)
- Isidoro Feliciello
- Department of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia.,Dipartimento di Medicina Clinica e Chirurgia, Universita' degli Studi di Napoli Federico II, Naples, Italy
| | - Željka Pezer
- Department of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Antonio Sermek
- Department of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | | | - Sven Ljubić
- Department of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia
| | - Đurđica Ugarković
- Department of Molecular Biology, Ruđer Bošković Institute, Zagreb, Croatia.
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17
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Grzybkowska D, Nowak K, Gaj MD. Hypermethylation of Auxin-Responsive Motifs in the Promoters of the Transcription Factor Genes Accompanies the Somatic Embryogenesis Induction in Arabidopsis. Int J Mol Sci 2020; 21:E6849. [PMID: 32961931 PMCID: PMC7555384 DOI: 10.3390/ijms21186849] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 09/09/2020] [Accepted: 09/16/2020] [Indexed: 12/17/2022] Open
Abstract
The auxin-induced embryogenic reprogramming of plant somatic cells is associated with extensive modulation of the gene expression in which epigenetic modifications, including DNA methylation, seem to play a crucial role. However, the function of DNA methylation, including the role of auxin in epigenetic regulation of the SE-controlling genes, remains poorly understood. Hence, in the present study, we analysed the expression and methylation of the TF genes that play a critical regulatory role during SE induction (LEC1, LEC2, BBM, WUS and AGL15) in auxin-treated explants of Arabidopsis. The results showed that auxin treatment substantially affected both the expression and methylation patterns of the SE-involved TF genes in a concentration-dependent manner. The auxin treatment differentially modulated the methylation of the promoter (P) and gene body (GB) sequences of the SE-involved genes. Relevantly, the SE-effective auxin treatment (5.0 µM of 2,4-D) was associated with the stable hypermethylation of the P regions of the SE-involved genes and a significantly higher methylation of the P than the GB fragments was a characteristic feature of the embryogenic culture. The presence of auxin-responsive (AuxRE) motifs in the hypermethylated P regions suggests that auxin might substantially contribute to the DNA methylation-mediated control of the SE-involved genes.
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Affiliation(s)
| | | | - Małgorzata D. Gaj
- Faculty of Natural Sciences, Institute of Biology, Biotechnology and Environmental Protection, University of Silesia in Katowice, Jagiellońska 28, 40-032 Katowice, Poland; (D.G.); (K.N.)
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18
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Singh S, Geeta R, Das S. Comparative sequence analysis across Brassicaceae, regulatory diversity in KCS5 and KCS6 homologs from Arabidopsis thaliana and Brassica juncea, and intronic fragment as a negative transcriptional regulator. Gene Expr Patterns 2020; 38:119146. [PMID: 32947048 DOI: 10.1016/j.gep.2020.119146] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 08/26/2020] [Accepted: 09/08/2020] [Indexed: 11/26/2022]
Abstract
Intra- and epicuticular-waxes primarily comprising of very long chain aliphatic lipid (VLCFA), terpenoids and secondary metabolites such as sterol and flavonoids played a major role in successful colonization of terrestrial ecosystem by aquatic plants and are thus considered as a key evolutionary innovation. The key rate limiting step of Fatty Acid (FA) biosynthesis of condensation/elongation are catalyzed by the enzyme, β-ketoacyl coenzyme A synthase (KCS), part of FAE (Fatty Acid Elongase) complex. KCS6 has been shown to be responsible for elongation using C22 fatty acid as substrate and is considered essential for synthesis of VLCFA for cuticular waxes. Earlier studies have established KCS5 as a close paralog of KCS6 in Arabidopsis thaliana, albeit with non-redundant function. We subsequently established segmental duplication responsible for origin of KCS6-KCS5 paralogy which is exclusive to Brassicaceae. In the present study, we aim to understand impact of duplication on regulatory diversification and evolution, through sequence and functional analysis of cis-regulatory element of KCS5 and KCS6. High level of sequence variation leading to conservation of only the proximal end of the promoter corresponding to the core promoter was observed among Brassicaceae members; such high diversity was also revealed when sliding window analysis revealed only two to three phylogenetic footprints. Profiling of transcription factor binding sites (TFBS) across Brassicaceae shows presence of light, hormone and stress responsive motifs; a few motifs involved in tissue specific expression (Skn-1; endosperm) were also detected. Functional characterization using transcriptional fusion constructs revealed regulatory diversification when promoter activity of homologs from A. thaliana and Brassica juncea were compared. When subjected to 5-Azacytidine, altered promoter activity was observed, implying role of DNA methylation in transcriptional regulation. Finally, investigation of the role of an 87 bp fragment from first intron that is retained in a splice variant, revealed it to be a transcriptional repressor. This is a first report on comparative sequence and functional analysis of transcriptional regulation of KCS5 and KCS6; further studies are required before manipulation of cuticular waxes as a strategy for mitigating stress.
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Affiliation(s)
- Swati Singh
- Department of Botany, University of Delhi, Delhi, 110007, India
| | - R Geeta
- Department of Botany, University of Delhi, Delhi, 110007, India
| | - Sandip Das
- Department of Botany, University of Delhi, Delhi, 110007, India.
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19
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First Come, First Served: Sui Generis Features of the First Intron. PLANTS 2020; 9:plants9070911. [PMID: 32707681 PMCID: PMC7411622 DOI: 10.3390/plants9070911] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 07/15/2020] [Accepted: 07/17/2020] [Indexed: 02/07/2023]
Abstract
Most of the transcribed genes in eukaryotic cells are interrupted by intervening sequences called introns that are co-transcriptionally removed from nascent messenger RNA through the process of splicing. In Arabidopsis, 79% of genes contain introns and more than 60% of intron-containing genes undergo alternative splicing (AS), which ostensibly is considered to increase protein diversity as one of the intrinsic mechanisms for fitness to the varying environment or the internal developmental program. In addition, recent findings have prevailed in terms of overlooked intron functions. Here, we review recent progress in the underlying mechanisms of intron function, in particular by focusing on unique features of the first intron that is located in close proximity to the transcription start site. The distinct deposition of epigenetic marks and nucleosome density on the first intronic DNA sequence, the impact of the first intron on determining the transcription start site and elongation of its own expression (called intron-mediated enhancement, IME), translation control in 5′-UTR, and the new mechanism of the trans-acting function of the first intron in regulating gene expression at the post-transcriptional level are summarized.
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